Encryption that uses the same key for both encryption and decryption.
- Block Cipher
- Encrypts data in single “chunks.” e.g. 128-bit chunks
- Data Encryption Standard (DES)
Uses 64-bit block and 56-bit key
- Susceptible to brute force attacks
- Attempted secure derivatives:
- 3DES, International Data Encryption Algorithm (IDEA), and Blowfish
- Attempted secure derivatives:
- Susceptible to brute force attacks
- Stream Cipher
- Encrypts data on-the-fly a single bit at a time.
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Revest Cipher 4 (RC4)
- Stream cipher
- 2001-2013 weaknesses discovered in RC4
- Considered insecure and a legacy cipher
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Advanced Encryption Standard (AES)
- Block cipher
- Uses 128-bit block size and 128-, 192-, or 256-bit key size
- Very secure and practically uncrackable
- Very fast
- Not just limited to TCP/IP apps, also TLS
- Many TCP/IP apps still moving towards adoption
- Block cipher
- Extended markdown support in VimWiki, for example, definitions